Phthalic acid esters of monoethers of hydroquinone



Patented June 6, 1933 UNITED STATES TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A

NEW YORK No Drawing.

This invention relates to phthalic acid esters of monoethers of hydroquinone. An object of our invention is to provide phthalic acid esters wherein each of the carboxyl groups of the phthalic acid is esterified by a monoether of hydroquinone. Another object of our invention is to provide a process of making these esters. I

YVe have discovered that phthalic acid esters of monoethers of hydroquinone, such, for

' instance, as the phthalic acid ester of the monomethyl ether of hydroquinone and the phthalic acid ester of the monobenzyl ether of hydroquinone, wherein both carboxyl groups of phthalic acid are esterified by the ether of hydroquinone, may be prepared by heating the ether of hydroquinone with phthalyl chloride. It is preferable to use approximately two molecular proportions of the ether of hydroquinone to one molecular proportion of phthalyl chloride. The temperature used should not be high enough to cause appreciable decomposition of the starting materials or of the product. As a rule, the temperature of the steam bath is suitable. In order to obtain a good yield, heating should be continued as long as hydrogen chloride is evolved. In some cases, as in the preparation of the phthalic acid ester of the monobenzyl ether of hydroquinone, it is desirable to carry out the reaction in the presence of a solvent or diluent, such, for instance, as toluene.

Our novel esters are useful as ultra-violet light filters in cellulose acetate compositions. Such compositions are claimed in our copending application Serial No. 626,218, filed of even date herewith.

As examples of the method of carrying out our invention, We shall describe the preparation of the phthalic acid ester of the monomethyl ether of hydroquinone and of the phthalic acid ester of the monobenzyl ether of hydroquinone. We have found'that it is immaterial whether the phthalyl chloride used is the symmetrical or the unsymmetrical modification, the same product being ob tained in either case. The monomethyl and monobenzyl ethers of hydroquinone have been describedin the literature.

PATENT" OFFICE} CYRIL J. STAUD AND THOMAS F. MURRAY, JR, OF ROGHESTER, NEVT YORK, ASSIG-NORS PH'IHALIC ACID ESTERS 0F Mo oia'rHERs 0F HYDROQUINONE i Application filed July 29, 1932. Serial No. 626,217.

' Preparation 0f the phthalic acid ester of the monomethyl ether offhydrogwlnoheffll grams of phthalyl chloride and 25 grams of the monomethyl ether of hydroquinone are heated together ona steam" bath until no more hydrogen chloride is evolved. A red,

ing for about 36 hours. This consists principally of the phthalic acid ester of themonomethyl ether of hydroquinone, which has the structural formula:

It may be purified by dissolving in of 95% ethyl alcohol and filteringwith the aid of activated charcoal. WVhen the filtrate is cooled, crystals separate out, "which may be further purified'by again recrystallizing from alcohol. The final productha's amelting point of 93 0., is-very's'olublein aceton and practically insoluble in ligroin.

Preparation of the phthalic acid ester 0 the monobenzyl ether of hycZMg'm'none-QO grams of phthalyl chloride and 40 grams. of the monobenzyl etherof hydroquinone, together with some toluene as a solvent, .are heated on a steam bath for about 18 hours, or until hydrogen chloride ceases to be evolved. On cooling, crystals of the phthalic acid ester CORPORATION OF oily liquid results which crystallizes on stand- 7 of the monobenzyl ether of hydroquinone separate. After being washed with toluene and dried, the white crystals melt at 144145 C. The structural formula of the product is Irwin o. understood that in the above examples the quantities may be varied, and that of the phthalic acid esters of the monomethyl and monobenzyl ethers of hydroquinone, it will be obvious that our invention is not limited to the esters of 7 these particular ethers. The phthalic acid esters of other a a lnonoalkyl or m'onoaryl ethers of hydroi i i a quinone, such, forinstance, as the pht-halic acid esters of the monoethyl and monophenyl ethers of hydroquinone may also he prepared by our process, and are included within the scope of our invention.

What we claim as our invention and desire 1 toebe secured by Letters Patentof the United States is:

1. Phthalic acid esters wherein both carboxyl groups of the phthalic acid are esterified by a monoether ofhydroquinone.

2. Phthali c acid esters wherein both cara I boxyl groups of the phthalic acid are esterified by a inonoalkylether ofhydroquinone. I I v 3. Phthalic acidesters wherein both can I hoxyl groups of the phthalic acid are ester-i" 2 fied by a monoaryl' ether of hydroquinone. I

4. A process of preparing phthalic acid I esters wherein bothcarboxyl groups of the v a phthalic acid are esterified by'amonoether of I I I I I I I 1 hydroquinone, comprising heating phthalyle chloride with a lnonoetherof hydroquinone; Y

5. A process of preparing phthalic acid *esters wherein both carboxyl groups of the r y y r p r a I I v phthalic' acid are esterified by a lnonoalkyl a v I i Q i ether of hydroquinone,comprising heating V phthalyl chloridewith a inonoalkyl ether of a hydroquinone.

6. A process of preparing phthalic ,acid esters wherein both carbonyl groups oithe a phthalic acid are'est'erified loya inonoaryl I I I I i ether of hydroquinone, comprisingheating a a p p c vi phthalyl chloride with a monoaryl ether of iydroquinone.

Signed at Rochester, New York, this 2211 day of July 1932.

CYRIL J. STAUD.

THOMAS F. MURRAY, JR. 

